A so-called heat mode recording material is known as an information recording medium, utilizing the physical variation of the medium caused by the heat as generated by irradiation or absorption of a light having a high density energy such as a laser ray to the medium. In recent years, liquid crystal-containing systems have been investigated from the viewpoint of imparting an erasability to the recording media of this kind.
In the case of such systems, for example, a liquid crystal placed and sealed in a cell is vertically oriented, and a local part of the cell is heated to form an isotropic state. Then, after cooling, a light-scattering structure is formed, which is to be a recording point. This part is heated and then cooled while an electric charge is imparted thereto, whereby this is again back to the previous vertically oriented state. This corresponds to the erasing procedure. When a laser ray or the like which has a reduced beam diameter is used as a heating means during recording, information recording media with high density recording and erasure ability can be obtained. For instance, one example of this type is described in U.S. Pat. No. 4,405,993, British Patent Publication No. 2,090,673. However, the liquid crystals used in the above art are of low molecular weight, and have a low phase transition point between the liquid crystal phase and the isotropic liquid phase. That is, the clearing point thereof is low, falling within the range of from 50.degree. C. to 60.degree. C. or below, and therefore are poor in preservation stability and are defective. In addition, as the liquid crystal is in the form of a liquid state in the cell, this is mobile in the cell and the recording point is often broken, which is another defect. In order to overcome the latter defect, a means has been developed to provide a partition wall in the cell, as described in Japanese Patent Application (OPI) No. 100247/83 (the term "OPI" as used herein refers to a " published unexamined Japanese patent application"), which, however, causes complication of the manufacture process and the elevation of the manufacture cost.
The above-mentioned defects are believed to be overcome by the use of polymeric liquid crystals, as described in Japanese Patent Application (OPI) No. 125247/83 and German Patent Application (OLS) No. 3,324,770.
However, polymeric liquid crystals are defective, as compared with low molecular weight liquid crystals, in that it is difficult to achieve a vertically oriented state even after impartation of an electric charge thereto. Specifically, these would involve a strong double refraction or would partially involve a light-scattering structure which is inherently formed during recording. As a result, the error rate in the recorded points would become high, whereby the characteristics of the information recording media becomes extremely poor. In addition, the use of optical elements having such polymeric liquid crystals in displays is undesirable as causing the disorder of images formed.